The Dean-Tolleson line is the point at which a hitter goes below the value of pitchers' hitting card #1. It is named for the performances of 1971 Padres' utility infielder Tommy Dean and 1982 Rangers' utility infielder Wayne Tolleson, both of whom hit .114 and whose S-O-M hitting cards resemble the pitcher hitting card #1.(See Tommy Dean On The Bump? thread in Baseball section).

I will elaborate on this at the Lau/Hriniak Replay Centre as I am about to discuss 1982 Matt Sinatro, who hit below the Dean-Tolleson line and how S-O-M dealt with that when considering his lefty/righty hitting splits.